This paper proposed a method to improve the safety of shell and tube heat exchangers by adding a heat insulation layer at the inlet end of the heat exchange tube. Based on the SIMPLE algorithm, the transient change model of end temperature difference of three?dimensional shell and tube heat exchanger was established, and the effects of the changes of insulation thickness and insulation material on the safety of heat exchanger were compared. The results show that the temperature difference between the two sides of the heat exchange tube is significantly reduced when the pipe end insulation layer is installed, regardless of the material of the pipe end insulation layer; The greater the thickness of the insulation layer at the pipe end and the thermal conductivity of the insulation material, the greater the reduction of temperature difference, instantaneous thermal shock stress and temperature difference thermal stress on both sides of the heat exchange tube, and the higher the safety of the heat exchanger; When the thickness of the pipe end insulation layer is 247.5 mm and the thermal conductivity is 2.090 0 W/(m?K), the maximum instantaneous temperature difference on both sides of the heat exchange pipe can be reduced by 10.1%, the maximum temperature difference can be reduced by 12.5% during stable operation, and the instantaneous thermal shock stress and temperature difference thermal stress can be reduced by 10.1% and 12.5%.

Energy shortage and environmental pollution have always been the focus of the world's attention. The use of oil, natural gas, and electricity to heat crude oil has high energy consumption and serious environmental pollution. Solar energy, as sustainable and clean energy, has become the focus of researchers from all over the world.Thus, a solar heating crude oil system was designed, and safe and easily available air was selected as the heat transfer fluid. The system consists of a solar receiver, a heat accumulator, a crude oil heat exchanger, and an electro?thermal furnace. The heat receiver receives solar radiation and the temperature rises. The air passes through the heat absorber to obtain high temperature, and the high temperature air enters the heat exchanger to heat the crude oil. A mathematical model for the analysis of the thermodynamic performance of the solar heating crude oil system was established, and the model was verified. Then, the Aspen Plus software was used to conduct thermodynamic analysis of the heatingprocess. The results show that the compressor and the preheater are the components with large exergy loss. When the pressure ratio of the compressor is 2.7, the system reaches its best state. At this situation, the thermal efficiency is 72.35%, the exergy efficiency is 73.89%, and the waste heat recovery efficiency is 72.33%.